A stereo microscope or stereoscope is really a pair of microscopes -- one for each eye that enables you to see objects in their true three-dimensional form. In other words, it is a high-powered magnifying glass! A true stereoscope will always have two eyepieces (binocular) with matching objectives for each eye. Slides are generally not used with a stereoscope (but can be) because of its lower magnification than a compound. It's certainly our family's favorite microscope!